[Bug 2001332] New: pango-view with --backend=ft2 and ---antialias=none generates antialiased renderings

https://bugzilla.redhat.com/show_bug.cgi?id=2001332

Bug ID: 2001332
           Summary: pango-view with --backend=ft2 and ---antialias=none
                    generates antialiased renderings
           Product: Fedora
           Version: 34
          Hardware: x86_64
                OS: Linux
            Status: NEW
         Component: pango
          Severity: high
          Assignee: [e-mail]
          Reporter: [e-mail]
        QA Contact: [e-mail]
                CC: [e-mail],
                    [e-mail],
                    [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail],
                    [e-mail]
  Target Milestone: ---
    Classification: Fedora

Created attachment 1820649
  --> https://bugzilla.redhat.com/attachment.cgi?id=1820649&action=edit
image showing the problem

Description of problem:

Hello Fedora Team,

I have a recently updated Fedora 34 installation.

The problem I want to report is that it looks like
the pango-view tool is always turning antialiasing on
when one uses the FreeType backend --backend=ft2,
even when one explicitly switches antialiasing off with --antialias=none,
whereas it works for the --backend=cairo option.

A second question would be if the FreeType backend
generally doesn't/can't support --antialias=none?
I tried to find some examples in C with antialising turned off
but I wasn't successful.

I must confess I didn't check other distributions.

As pango-view is regarded as a tool for creating minimal reproducers
against the font rendering stack, I dare to set the severity to 'high' :-)

Best Regards
Andre

Version-Release number of selected component (if applicable):

$ uname -a
Linux localhost.localdomain 5.13.13-200.fc34.x86_64 #1 SMP Thu Aug 26 17:06:39
UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

$ dnf list installed | grep dejavu
dejavu-lgc-sans-fonts.noarch                2.37-16.fc34                       
@fedora
dejavu-lgc-sans-mono-fonts.noarch           2.37-16.fc34                       
@fedora
dejavu-lgc-serif-fonts.noarch               2.37-16.fc34                       
@fedora
dejavu-sans-fonts.noarch                    2.37-16.fc34                       
@fedora
dejavu-sans-mono-fonts.noarch               2.37-16.fc34                       
@fedora
dejavu-serif-fonts.noarch                   2.37-16.fc34                       
@fedora

$ dnf list installed | grep ImageMagick
ImageMagick.x86_64                          1:6.9.11.27-3.fc34                 
@fedora
ImageMagick-libs.x86_64                     1:6.9.11.27-3.fc34                 
@fedora

$ dnf list installed | grep pango
pango.i686                                  1.48.9-2.fc34                      
@updates
pango.x86_64                                1.48.9-2.fc34                      
@updates
pango-devel.x86_64                          1.48.9-2.fc34                      
@updates
pangomm.x86_64                              2.46.1-1.fc34                      
@updates

$ dnf list installed | grep freetype
freetype.i686                               2.10.4-3.fc34                      
@fedora
freetype.x86_64                             2.10.4-3.fc34                      
@fedora
freetype-devel.x86_64                       2.10.4-3.fc34                      
@fedora

$ dnf list installed | grep fontconfig
fontconfig.i686                             2.13.94-2.fc34                     
@updates
fontconfig.x86_64                           2.13.94-2.fc34                     
@updates
fontconfig-devel.x86_64                     2.13.94-2.fc34                     
@updates

$ dnf list installed | grep cairo
cairo.i686                                  1.17.4-3.fc34                      
@fedora
cairo.x86_64                                1.17.4-3.fc34                      
@fedora
cairo-devel.x86_64                          1.17.4-3.fc34                      
@fedora
cairo-gobject.i686                          1.17.4-3.fc34                      
@fedora
cairo-gobject.x86_64                        1.17.4-3.fc34                      
@fedora
cairomm.x86_64                              1.14.2-8.fc34                      
@fedora
python2-cairo.x86_64                        1.18.2-8.fc34                      
@fedora
python3-cairo.x86_64                        1.20.0-2.fc34                      
@fedora

How reproducible:

Always

Steps to Reproduce:

$ pango-view --no-display --dpi=72 --backend=cairo --antialias=none
--font="DejaVu Sans 38" --text="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
--output=abc-cairo-aa-none.png
$ pango-view --no-display --dpi=72 --backend=cairo --antialias=gray
--font="DejaVu Sans 38" --text="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
--output=abc-cairo-aa-gray.png
$ pango-view --no-display --dpi=72 --backend=cairo --antialias=subpixel
--font="DejaVu Sans 38" --text="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
--output=abc-cairo-aa-subpixel.png
$ pango-view --no-display --dpi=72 --backend=ft2 --antialias=none
--font="DejaVu Sans 38" --text="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
--output=abc-ft2-aa-none.png
$ pango-view --no-display --dpi=72 --backend=ft2 --antialias=gray
--font="DejaVu Sans 38" --text="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
--output=abc-ft2-aa-gray.png
$ pango-view --no-display --dpi=72 --backend=ft2 --antialias=subpixel
--font="DejaVu Sans 38" --text="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
--output=abc-ft2-aa-subpixel.png

$ gimp abc-*.png

Actual results:
Attached pngs.
The file abc-ft2-aa-none.png is in gray-scale and not as expected in
black-white.
The file abc-cairo-aa-none.png is in black-white as expected.

Expected results:
I would have expected the files abc*--aa-none.png looking near identical.

Additional info:

[Bug 2001332] pango-view with --backend=ft2 and ---antialias=none generates antialiased renderings

https://bugzilla.redhat.com/show_bug.cgi?id=2001332

--- Comment #1 from a3emdot  ---
Created attachment 1820650
  --> https://bugzilla.redhat.com/attachment.cgi?id=1820650&action=edit
image showing how it should look like

[Bug 2001332] pango-view with --backend=ft2 and ---antialias=none generates antialiased renderings

https://bugzilla.redhat.com/show_bug.cgi?id=2001332

Peng Wu  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
            Link ID|                            |GNOME Gitlab
                   |                            |GNOME/pango/-/merge_request
                   |                            |s/473
           Doc Type|---                         |If docs needed, set a value

[Bug 2001332] pango-view with --backend=ft2 and ---antialias=none generates antialiased renderings

https://bugzilla.redhat.com/show_bug.cgi?id=2001332

Peng Wu  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |POST

[Bug 2001332] pango-view with --backend=ft2 and ---antialias=none generates antialiased renderings

https://bugzilla.redhat.com/show_bug.cgi?id=2001332

--- Comment #2 from a3emdot  ---
I wonder if this patch made it to the new pango 1.49 branch

[Bug 2001332] pango-view with --backend=ft2 and ---antialias=none generates antialiased renderings

https://bugzilla.redhat.com/show_bug.cgi?id=2001332

--- Comment #3 from Peng Wu  ---
I think the patch is in pango 1.49.2.

Maybe you can try it on Fedora 35 Workstation.

[Bug 2001332] pango-view with --backend=ft2 and ---antialias=none generates antialiased renderings

https://bugzilla.redhat.com/show_bug.cgi?id=2001332

--- Comment #4 from a3emdot  ---
Oh I missed that somehow. perhaps I selected the wrong branch somehow,
while exploring the file tree, sorry for that.

For the moment I can't test on Fedora 35, because I have still no Fedora 35
available :-(

Thank you Peng Wu and kind regards
Andre

[Bug 2001332] pango-view with --backend=ft2 and ---antialias=none generates antialiased renderings

https://bugzilla.redhat.com/show_bug.cgi?id=2001332

--- Comment #5 from Ben Cotton  ---
This message is a reminder that Fedora Linux 34 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora Linux 34 on
2022-06-07.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with
a
'version' of '34'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, change the 'version' 
to a later Fedora Linux version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora Linux 34 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora Linux, you are encouraged to change the 'version' to a later version
prior to this bug being closed.

[Bug 2001332] pango-view with --backend=ft2 and ---antialias=none generates antialiased renderings

https://bugzilla.redhat.com/show_bug.cgi?id=2001332

Peng Wu  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |NEXTRELEASE
             Status|POST                        |CLOSED
        Last Closed|                            |2022-05-13 02:44:02

--- Comment #6 from Peng Wu  ---
I tested in Fedora 36, I think this bug is fixed now.